Along with the recent advancement of IT, there has been developed an inexpensive NAS file storage subsystem as a storage system capable of receiving file accesses from clients via the network and providing file services.
In a file storage system composed of a file storage subsystem receiving access requests from the clients and an archive subsystem coupled thereto, since only the file data having high access frequencies are stored in the file storage subsystem and other file data having low access frequencies are stored in the archive subsystem, and the file data are accessed via control information of the file storage subsystem, techniques are adopted to perform data migration and data copy among file storage subsystems and archive subsystems. One example of such data migration and data copy technique is illustrated in patent literature 1.
According to such a file storage system, in order to equalize the loads on physical resources within the system, the CPU utilization rate or the like is monitored, and when a file storage subsystem receiving high load is found, processes such as analysis of logs are performed in order to specify the cause of increased load, and thereafter, measures are taken to reduce (equalize) the load, such as changing the file storage destination or increasing the file storage subsystems.